Sprinkler systems in widespread use for protection against fire in buildings are provided with liquid discharge nozzles adjacent the ceilings so distributed that when the temperature in a zone reaches a predetermined point the fire suppressant is released for free sprinkling in the neighborhood of the excessive heat. Many types of ceilings are extensively damaged by the high velocity streams jetting from the nozzles and impinging on the ceilings; therefore, many attempts have been made, without good results, to effectively shield the ceiling against such damage while, at the same time, not adversely affecting fluid delivery or adequate spread of the spray pattern.
To solve the problem, a dome-shaped shield is mounted on the nozzle therearound to present a fluid-deflecting hood between the ceiling and the high velocity streams radiating from the nozzle. The inner concave surface of the hollow shield is so disposed relative to the fluid emanating radially from the nozzle as to avoid abrupt change in the direction of flow as the streams impinge thereon, and preclude jetting directly against the ceiling.
The result of such construction, without more, would be to unduly confine the spray around the nozzle and thereby undesirably reduce the area of fluid distribution within the space to be protected. Therefore, a portion of the fluid is permitted to escape through strategically located, slotted ports in the shield with the escaping fluid moving in low velocity plumes which cause no ceiling damage yet gravitate exteriory of the shield and merge with the primary streams in the required, wide-spread, spray pattern below the nozzle-deflector unit.